As conventional optical lenses such as photochromic lenses, inorganic lenses have generally been used. That is, usually, an organic coating layer with photochromic property was added to a surface of a glass or a surface of plastic lenses such as CR-39. Recently, as a lens itself, the use of plastic lenses with high impact resistance have spread. Particularly, in United States of America, lenses made from a polycarbonate have widely proliferated and demand for a sun glass with impact resistance has rapidly increased because of extensive outdoor activities.
As synthetic resin laminates with photochromism property, hitherto, a laminate obtained by adding a photochromic organic compound to a silicone surface curing coating agent and then coating it on one side of a substrate and then performing cure and a laminate obtained by adding a photochromic organic compound to an urethane coating agent and then coating it on one side of a synthetic resin laminate and then performing cure have been known (Japanese Patent Kokai (Laid-open) No. 63-178193).
However, in the process for coating a coating agent containing a photochromic organic compound on one side of a synthetic resin substrate, it was difficult to obtain a smooth coated film surface and to control a thickness of a coated film. Thus, when a coated film surface is not smooth, it is not practically preferable since use of the laminate as a photochromic lens causes distortion through the lens.
Further, Japanese Patent Kokai (Laid-open) No. 61-148048 discloses a photochromic laminate with a photochromic layer containing a spironaphtho oxazine derivative interposed between transparent material layers. Although the prior art discloses an example in which one liquid type polyurethane resin is contained in a photochromic layer, both a color development speed and a color disappearance speed are low, and thus that photochromic laminate is insufficient.
Moreover, also in photochromic lenses, various processes such as direct kneading into a resin and coating on a resin surface have been tried. However, they are not successful and are not put into practice because of performance problems due to insufficient heat resistance of the photochromic elements during kneading and, also due to problems in surface coating, and contrast shortage from limitation of coated film thickness.
Thus, in the present situation, there exists no transparent synthetic resin laminate with photochromism property as a photochromic lens in which both a color development speed and a color disappearance speed are high and surface smoothness of a coated film and control of coated film thickness in a photochromic layer are excellent.